FIELD OF THE INVENTION
This invention relates to a synchronizer having self-energizing and means to limit
force provided by the self-energizing means.
BACKGROUND OF THE INVENTION
Synchronizers for use in multi-ratio transmissions are well known. Such
synchronizers include pairs of friction and jaw members for respectively
synchronizing and positively clutching a gear to a shaft, pre-energizer assemblies
for engaging the friction members in response to initial engaging movement of a
shift sleeve, a hub rotatably fixed to the shaft and having external spline teeth
slidably receiving internal spline teeth of the shift sleeve which often defines one
of the jaw member pairs, a baulkring having blocker teeth for arresting engaging
movement of the shift sleeve until synchronization is reached and for transferring
a shift force from the sleeve to increase the engaging force of the friction
members.
It is also known that such synchronizers may be used to reduce shift time and
shift effort required by a vehicle operator by providing the synchronizes with self-
energizing means and that springs may be used to limit forces provided by the
self-energizing means. US-A-5 678 670 discloses a synchronizer having all of the
above features and US-A-5 544 727 discloses all but the spring regulating
feature.
SUMMARY OF THE INVENTION
An object of this invention is to provide a synchronizer with self-energizing and
improved force limiting of the self-energizing.
The invention relates to a synchronizer, as disclosed in US-A-5, 544. 727 which
represents the pre-characterizing part of claim. The synchronizer fictionally
synchronizes and positively connects first and second drives disposed for relative
rotation about a common axis, and the synchronizer comprises: A first element
affixed against rotation and axial movement relative to the first drive and has an
annular periphery with external splines.
A second element includes an annular periphery with internal splines defining
first jaw means and axially movable from a neutral position to an engaged
position with second jaw means for positively connecting the drives in response
to engaging movement of the second element by an axially directed first shift
force (Fo). The second element includes internal splines mating continuously
with the external splines in close slidable relation for
A first ring includes a first friction surface axially movable into engagement with a second
friction surface in response to the engaging movement of the second element for producing a
synchronizing torque (T0). First and second pluralities of blocker surfaces are movable into
engagement in response to the engaging movement of the second element for preventing
asynchronous engagement of the jaw means and for transmitting the first shift force (r0) to the
first friction surface to effect an engagement force of the friction surfaces. The second plurality
of blocker surfaces are affixed to the first ring. Pluralities of first and second self-energizing
means respectively include first and second ramps operative when engaged to react the
synchronizing torque for producing an additive axial force (ra) in the direction of the first shift
force (F0) and for increasing the engagement force of the friction surfaces. One of the first and
second self-energizing means includes means for directing the additive axial force (Fa) to the
first friction surface via the blocker surfaces. Each of the first self-energizing means are
mounted on one Oi the elements anu eao i Oi ti 16 seco nd self-energizing means are r IIUUI I ted
for non-radial movement and limited rotation relative to another of the elements.
*. , _ L,aooy^The improvement is characterized by resilient means for limiting the additive axial
* force to a predetermined amount. Each of the first self-energizing means including a member
movably mounted on the one of the elements and defining one of the first self-energizing
ramps. The member is movable against the resilient means in response to the additive axial
force (Fa) exceeding the predetermined amount.
Brief Description of the Drawings
The synchronizer of the invention is shown in the accompanying drawings in which:
Figure 1 is a sectional view of a double-acting baulkring-type synchronizer in a neutral
position and disposed for rotation about the axis of a shaft:
Figures 2 and 3 are relief views of broken away portions of components in Tigure 1
looking axially relative to the shaft;
Figure 4 is a vertical sectional view of a circled assembly in Figure 3.
Figure 5 is a relief view of a shift sleeve of the synchronizer in Figure 1, and with
components in figures 5 and G rotateu GO degrees relative to i igure 1;
Figure 6 is the assembled components of Figure 1 in the neutral position with the shift
sleeve of Figure 5 removed;
Figure 7 is a perspective view of a self-energizing member in Figures 1 and 6.
figures 8 and 9 are partial views of Tigure 6 with components therein in two different
engaged positions; and
Figure 10 is a sectional view of a self-energizing member in Figure 4 looking along line
a-a.
Detailed Description of the Drawings
The term "synchronizer" shall designate a clutch mechanism utilized to non-rotatably
couple a selected ratio gear to a shaft by means of a positive clutch in which attempted
engagement of the positive clutch is prevented until members of the positive clutch are brought
to substantially synchronous rotation by a synchronizing friction clutch associated with the
positive clutch. The term "self-energizing" shall designate a synchronizer which includes ramps
or cams or the like to increase the engaging force of the synchronizing proportion to the
synchronizing torque of the friction clutch.
Looking now at Figures 1-10, therein is shown a gear and synchronizer assembly 10
which forms part of a multi-ratio change speed transmission. Assembly 10 includes a shaft 12
mounteu ior rotation aucut a centra! axis 12a. axialiy spaceu apart gears 14,1o supported on
the shaft for rotation relative thereto and secured against axial movement relative to the shaft
in known manner, and a double-acting synchronizer 18.
The synchronizer 18 includes annular members 20,22 axialiy and rotatably affixed to
gears 14,16 in known manner, gear friction surfaces 24,26 herein integral with members 20.22,
gear jaw teeth 28,30 herein integral with members 20.22, a hub member 32 axialiy and
rotatably affixed at a central opening 32a thereof to shaft 12, a shift sleeve 34, internal spline
teeth 36 defined on a central opening of sleeve 34 and in constant mesh with external spline
teeth 38 defined on the outer circumference of hub 32. baulkrings 40.42, blocker teeth sets
44.46 and friction surfaces 48,50 herein integral with baulkrings 40.42. pre-energizer
assemblies 52, and a self-energizing/blocker assembly 54. Herein, the synchronizer includes
three circumferentially spaced apart self-energizing/blocker assemblies 54 which cooperate
with a like number of blocker teeth on each baulkring, and three circumferentially spaced apart
pre-energizer assemblies. Each blocker tooth 44.46 respectively includes angled blocker
surfaces 44a,44b,46a.46b.
As is readily seen, friction surfaces 24.48 and 26,50 pair up to define friction clutches
for synchronizing the gears to the shaft prior to engagement of the jaw clutch members. Cone
clutches are preferred: however, other types of friction clutches may be used. The friction
friction surfaces may be defined by any of several known friction materials
affixed to the base member, e,g... pyrolytic carbon friction materials such as
disclosed in U.S. Patents 4,700,823; 4,844,218 and 4,778,548 may be used.
Spline teeth 36, 38 have axially extending flank surfaces 36a, 38a which
continuously mate in close sliding relation so that there is relatively no free play
between shift sleeve 34 and shaft 12. Opposite ends of splines 36 define jaw
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the gears to the shaft. The flank sides of jaw teeth 36b, 36c and of gear jaw
teeth 28, 30 may be provided with an antibackout or a locking angle feature to
prevent inadvertent disengagement of the teeth. Details of this feature may be
seen by reference to U.S Patent 4,727,968.
Each pre-energizer assembly 52 includes a helical compression spring 58 and
plunger 60 disposed in a radially extending blind bore in hub 32 and biasing a
roller or ball 62 (herein a roller) into an annular detent groove 36d in shift sleeve
splines 36. Pre-energizer assembly 52 resiliency positions shift sleeve 34 in the
neutral position shown in Figure 1. Rollers 62 are axially spaced between
abutment surfaces 64a, 66a defined by a plurality of tabs 64, 66 (herein three)
formed integral with baulkrings 40, 42. The tabs extend into recesses 32b in
hub 32 for limiting rotation of the baulking relative to the hub and shaft.
When it is desired to coupled either gear to the shaft, an appropriate and
unshown shift mechanism, such as disclosed in U.S. Patent 4,920,815, moves
shift sleeve 34 axially via a partially shown shift fork 68 along the axis of shaft 12
either left to couple gear 14 or right to couple gear 16. The shift mechanism
may be manually moved by an operator through a linkage system, may be
selectively moved by an actuator, or may be moved by means which
automatically initiate shift mechanism movement and which also controls the
magnitude of the force applied by the shift mechanism. When the shift
mechanism is manually moved, pre-energizer assemblies apply a pre - energizer
force proportional to the force applied by the operator the shift sleeve. Whether
manually or automatically applied, the force is applied to the shift sleeve in an
axial direction and is proportional to a shift force hereinafter referred to as an
operator shift force F0. The pre-energizer force, depending on direction of shift
sleeve movement by the shift force (F0), moves either friction surface 48 or 50
into initial engagement with its associated friction surface to clock the associated
baulking to a position relative to hub 32 for positioning the self-energizing/
blocker assemblies 54 in a manner explained hereinafter.
The self-energizing / blocker assemblies 54 each include self-energizing
members 70, 72 the blocker teeth 44, 46, a rigid self- energizing / blocker
member 74 which reacts self energizing and blocker forces, and detent
assemblies 76, 78 respectively biasing members 70, 72 to the positions of Figure
6. Assemblies 76, 78 are identical; hence only assemble 76 is described in detail.
Assembly 76 includes a round headed detent member 80 biased into a detent
groove 70a in member 70 by a compression spring 81 disposed in a blind bore
32c in the hub. Member 70 is slidably disposed in a slot having axially extending
sidewalls 32d, 32e that diverge as they extend radially inward for slidably
embracing like diverging sidewalls 70b, 70c of member 70. The sidewalls prevent
radially outward movement of member 70. Detent groove 70a include detent
ramps 70d, 70e which prevent axial movement of member 70 until axial forces
acting on self - energizing or boost ramps 71a, 71b of member 70 exceed a
predetermined centering force provided by spring 81, and the curved centering
surface defined by groove 70a and detent ramps 70d, 70e. To prevent
interference of member 70 sidewalls with baulkrings 40, 42 when member 70
moves axially as seen in Figure 9, portions of axial ends of sidewalls 70b, 70c are
removed in a manner seen in Figure 10 for sidewall 70b.
Rigid member 74 includes circumferentially spaced apart end portions 82, 84
rigidly secured together by a circumferentially extending portion 86 received in a
circumferentially extending slot 34a in shift sleeve 34. Slot 34a allows limited
circumferential movement of member 74 therein relative to the sleeve and
prevents axial movement herein relative to the sleeve. End portion 82 includes
self - energizing ramp surfaces 82a, 82b which respectively react against self -
energizing ramp surfaces 71a, 71b when shift sleeve 34 is moved axially left or
right and blocker surfaces 82c, 82d which respectively react against blocker
surfaces 44a, 46a of blocker teeth 44, 46. In a like manner, end portion 84
includes self - energizing ramp surfaces 84a, 84b for respectively reacting
against self - energizing ramp surfaces 73a, 73b and blocker surfaces 84c, 84d
which respectively react against blocker surfaces 44b, 46b. Non - self -
energizing ramp surfaces 82e, 84e respectively react against surfaces 71c, 73c
when the synchronizer is in the neutral position of Figures 1 and 6. The engaged
position of the non - self - energizing surfaces prevents unwanted activation of
the self - energizing ramp surfaces in the event there is some amount of torque
produced by one of the cone dutches, e. g. viscous shear of oil between the
cone clutch friction surfaces may produce a torque that could otherwise activate
the ramps.
Function of self - energizing / blocker assemblies 76 are described relative to
Figures 1 and 6-9. The description assumes as asynchronous condition in one
direction exists between shaft 12 and gear 16. When the blocker and self -
energizing ramp surfaces are engaged as shown in Figure 8 friction surfaces 50,
26 are also engaged. Axial extensions 44c, 46c of blocker teeth 44, 46 keep the
blocker teeth circumferentially positioned between end portions 82, 84.
Asynchronous conditions in the other direction or for gear 14 produce surface
engagements that should be obvious from the following description. Figure 6
illustrates a "neutral position" of all synchronizer components. Initial rightward
axial movement of shift sleeve 34 by the operator shift force F0 is transmitted by
pre - energizer rollers 62 to baulkring 42 via tab abutment surfaces 66a to effect
initial frictional engagement of movable cone surface 50 with gear cone surface
26, thereby producing an initial synchronizing torque for rotating blocker surfaces
46a to positions ensuring contact with blocker surfaces 82d. The initial rightward
movement also moves rigid member 74 enough for non - self- energizing ramp
surfaces 71c, 82e to axially disengage and allow the initial synchronizing torque
to engage blocker surfaces 82b, 46am, as seen in Figure 8. The initial
engagement force of the cone surface is, of course, a function of the force of
spring 58 and the angles of the walls of detent grooves 36d. In the 'blocking /
self - energizing position' of Figure 8, the torque has rotated baulkring 42 and
rigid members 74 enough to also engage self - energizing ramp surfaces 71b,
82b. Hence, Figure 8 surfaces 82d, 82b are trapped between baulkring blocker
surfaces 46a and self - energizing ramp surfaces 71b. When these surfaces are
so trapped and ignoring the effect of the engaged self - energizing ramp
surfaces 82b, 71b, full operator shift force F0 applied to rigid member 74 from
shift sleeve 34 is transmitted across blocker surfaces 82d, 46a, thereby engaging
friction surfaces 26, 50 with the operator shift force F0 for producing a
synchronizing torque T0 proportional to the operator shift force F0. Since blocker
surfaces 82d, 46a are oblique to the plane of rotation, they in addition to
preventing asynchronous engagement of jaw teeth 36a, 30 and transmitting the
shift force F0 to friction surfaces 26, 50, also produce a counter torque or
unblocking torque counter to the synchronizing torque but of lesser magnitude
during asynchronous conditions. As substantial synchronism is reached, the
synchronizing torque drops below the unblocking torque, whereby the blocker
teeth move out of engagement to allow continued axial movement of the shift
sleeve and engagement of movable jaw teeth 36c with gear jaw teeth 30.
surfaces, thereby further increasing the engaging force of the friction surfaces to provide an
additive synchronizing torque Ta which adds to the torque T0.
In the event that the self-energizing additive axial force Fa exceeds a predetermined
amount, as determined by detent assemblies 76, member 70 will move leftward, as shown in
Tigure 9. and allow non-self-energizing surfaces 82e to move into balance positions. When in
the balance positions, self-energizing ramp surfaces 82b.71b are engaged and non-self-
energizing surfaces 82e engage axially extending surface portions 32f of sidewall 32d in hub
32 which do not produce an axial additive force component. When in this position, the
maximum additive force Ta is limited to the force reacted by the detent assemblies 76 at the
balance position since any synchronizing torque increase will be reacted by the non-self-
energizing surfaces 82c,32f.
The predetermined amounted of axial force provided by the detent assemblies 76,78
may be different for gears 14,16 and for up and down shifts by varying the angles of the detent
ramps 70d,70e in each of members 70.72.
A synchronizer with self-energizing has been disclosed. The following claims are
intended to cover the inventive portions of the disclosed synchronizer.
We Claim
1. A synchronizer (18) for frictionally synchronizing and positively connecting
first and second drives (12, 16) disposed for relative rotation about a
common axis (12a); the synchronizer comprising:
a first element (32) affixed against rotation and axial movement
relative to the first drive (12) and having an annular periphery with
external splines (38);
a second element (34) having an annular periphery with internal
splines (36) defining first jaw means (36c) and axially movable from a
neutral position to an engaged position with second jaw means (30) for
positively connecting the drives (12, 16) in response to engaging
movement of the second element (34) by an axially directed first shift
force (F0), the second element comprising internal splines (36) mating
continuously with the external splines (38) in close slidably relation for
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a first ring (42) having a first friction surface (50) axially movable
into engagement with a second friction surface (26) in response to the
engaging movement of the second element (34) for producing a
synchronizing torque (T0);
first and second pluralities of blocker surfaces (82d, 46a) movable
into engagement in response to the engaging movement of the second
element (34) and an asynchronous rotation between the first and second
drives in one direction for preventing asynchronous engagement of the
jaw means (36c, 30) and for transmitting the first shift force (F0) to the
first friction surface (50) to effect an engagement force of the friction
surfaces, the second plurality of blocker surfaces (46a) affixed to the first
ring (42);
pluralities of first an second self - energizing means (70, 82)
respectively having first and second ramps (71b, 82b) operative when
engaged to react the synchronizing torque for producing an additive axial
force (Fa) in the direction of the first shift force (F0) and for increasing the
engagement force of the friction surfaces (50, 26), one (82) of the first
and second self - energizing means having means for directing the
additive axial force (Fa) to the first friction surface (50) via the blocker
surfaces (82d), each first self - energizing means (70) mounted on one of
the elements (32), and each second self - energizing means (82)
mounted for non - radial movement and limited rotation relative to
another of the elements (34); characterized by comprising;
resilient means (81) for limiting the additive axial force to a first
predetermined amount;
each first self - energizing means (70) having a first member (70)
movably mounted on the one of the elements (32) and defining one of the
first self - energizing ramps (71b), and the first member movable against
the resilient means (81) in response to the additive axial force (Fa)
exceeding the predetermined amount. /^tTof /A/r>
2. The synchronizer as claimed in claim 1, comprising:
a third drive (14) disposed for rotation about the common axis
(12a) relative to the first and second drives (12, 16) and axially spaced
from the second drive (16);
the second element (34) internal splines (36) defining third jaw
means (36b) axially movable from a neutral position to an engaged
position with fourth jaw means (28) for positively connecting the first and
third drives (12, 14) in response to engaging movement of the second
element (34) by an axially directed second shift force (P0);
a second ring (40) having a third friction surface (48) axially
movable into engagement with a fourth friction surface (24) in response
to the engaging movement of the second element (34) by the second shift
force (Fo) for producing a synchronizing torque (T0);
third and fourth pluralities of blocker surfaces (82c, 44a) movable
into engagement in response to the engaging movement of the second
element (34) by the second shift force (Fo) for preventing asynchronous
engagement of the third and fourth jaw means (36b,28) and for
transmitting the second shift force (Fo) to the third friction surface (48) to
effect an engagement force of the third and fourth friction surfaces
(48,24), the fourth plurality of blocker surfaces (24a) affixed to the second
ring (40); ^-—^"--------
the pluralities of first and second self-energizing means (70, 82)
respectively having third and fourth ramps (7la, 82a) operative when
engaged to react the synchronizing torque for producing a second additive
axial force (Fa) in the direction of the second shift force (Fo) and for
increasing the engagement force of the third and fourth friction surfaces
(48, 24), one (82) of the first and second self-energizing means (82c)
comprising means for directing the second additive axial force (Fa) to the
third friction surface (48) via the third and fourth blocker surfaces (82c,
44a) and each member (70) defining one of the third self-energizing
ramps (71a) and the member movable against the resilient means in
response to the second additive axial force (Fa) exceeding a second
predetermined amount.
3. The synchronizer as claimed in claim 1 or 2, wherein:
the periphery of the first element (32) having axially extending
recesses (32d, 32e) each slidably receiving one of the members (70) for
axial movement against the resilient means (81) from a first position in a
direction opposite the shift force (FD) applied to the second element (34)
in response to the additive axial force (Fa) produced by the engaged
ramps (71a, 82a) exceeding the predetermined amount in the direction of
the shift force (Fo) applied to the second element.
4. The synchronizer as claimed in claim 3, wherein:
a radially inward facing surface of each member (70) comprises a
curved centering surface (70a, 7Gd, 70e) acted on by the resilient means
for positioning the member in the first position and operative to move
the resilient means (81) radially inward in response to the additive axial
force (Fa) exceeding the either of the first and second predetermined
amount.
5. The synchronizer as claimed in claim 1-4, comprising:
fifth and sixth pluralities of blocker surfaces (84d, 46b) movable
into engagement in response to the engaging movement of the second
element (34) and an asynchronous rotation between the first and second
drives in a direction opposite the one direction for preventing
asynchronous engagement of the jaw means (36c, 30) and for
transmitting the first shift force (Fo) to the first friction surface (50) to
effect an engagement force of the friction surfaces (50, 26), the sixth
plurality of blocker surfaces (46b) affixed to the first ring (42);
pluralities of third and fourth self-energizing means (72, 84)
respectively having fifth and sixth ramps (73b, 84b) operative when
engaged to react the synchronizing torque for producing a third additive
axial force (Fa) in the direction of the first shift force (Fo) and for
increasing the engagement force of the friction surfaces (50, 26), one
(84) of the third and fourth self-energizing means comprising means (84d)
for directing the third additive axial force (Fs) to the first friction surface
(50) via the fifth and sixth pluralities of blocker surfaces (84d, 46b) each
third self-energizing means (72) mounted on one of the elements (32),
and each fourth sejf-energizing means (84) mounted for ran-fad ja I
movement and limited rotation relative to another of the elements (34);
second resilient means (81) for limiting the additive axial force of
third and fourth self-energizing means (72, 84) to a third predetermined
amount;
each third self-energizing means (72) having a second member
(72) movably mounted on the one of the elements (32) at a position
circumferentially spaced from the first member (70) and defining one of
the fifth self-energizing ramps (73b), the second member movable against
the resilient means (81) in response to the third additive axial force (Fa)
exceeding the third predetermined amount, and a circumferentially
extending member (86) rigidly securing the second and fourth self-
energizing means (82,84) together circumferentially between the first and
second members (70, 72).
6. The synchronizer as claimed in claim 5, comprising:
seventh and eighth pluralities of blocker surfaces (84c, 44b)
movable into engagement in response to the engaging movement of the
second element by the second shift force (Fo) for preventing
asynchronous engagement of the third and fourth jaw means (36b, 28)
and for transmitting the second shift force (Fo) to the third friction surface
(48) to effect an engagement force of the third and fourth friction
surfaces (48, 24), the eighth plurality of blocker surfaces (44b) affixed to
the second ring (40);
the pluralities of third and fourth self-energizing means (72, 84)
respectively having seventh and eight ramps (73a, 84a) operative when
engaged to react the synchronizing torque for producing a fourth additive
axial force (Fa) in the direction of the second shift force (Fo) and for
increasing the engagement force of the third and fourth friction surfaces
(48, 24), one of the third and fourth self-energizing means (84) having
means (84c) for directing the fourth additive axial force (Fa) to the third
friction surface (48) via the seventh and eight blocker surfaces (44b, 84c),
and each second member (72) defining one of the seventh self-energizing
ramps (73a) and the second member (72) movable against the second
resilient means (81) in response to the fourth additive axial force (Fa)
exceeding a fourth predetermined amount.
7. The synchronizer as claimed in claim 5 or 6, wherein:
the periphery of the first element (32) comprising axially
extending second recesses (32d, 32e) each slidably receiving one of the
second members (72) for axial movement against the second resilient
means (81) from a first position in a direction opposite the shift force (Fo)
applied to the second element (34) in response to the fourth additive axial
force (Fa) produced by the engaged ramps exceeding the fourth
predetermined amount in the direction of the shift force (Fo) applied to
the second element.
8. The synchronizer as claimed in claim 7, wherein:
a radially inwardly facing surface of each member (70, 72)
comprises a curved centering surface (70a, 70d, 70e) acted by the
resilient means (81) for positioning the members (70, 72) in the first
positions and operative to move the resilient means radially inwardly in
response to the additive axial forces (Fa) exceeding the predetermined
amounts.
9. The synchronizer as claimed in each of the preceding claim, wherein:
the first element (32) is a hub, the second element (34) is a shift
sleeve, the first friction ring (42) is a baulkring having the second
pluralities of blocker surfaces affixed thereto, the second self-energizing
means (82) comprises the means for directing the additive axial force (Fa)
to the first friction surface (50) via the blocker surface (82d), the first self-
energizing means (70) are mounted on the hub (32), and the second self-
energizing means are mounted for non-radial movement and non-axial
movement relative to the shift sleeve and for limited rotation relative to
the shift sleeve.

The invention relates to a baulkring-type synchronizer (18) includes cone clutch
friction surfaces (24, 48 and 26, 50) and jaw clutch teeth (36b, 28 and 36c, 30)
for frictionally synchronizing and positive connecting gears (14, 16) to a shaft
(12). A plurality of rigid members (72) are drivingly interposed between blocker
teeth (44, 46) affixed to baulkrings (40, 42) and self-energizing ramp surfaces
(71a, 71b, 73a, 73b) on self-energizing members (70, 72) mounted on an outer
circumference of a hub 32 affixed to the shaft (12). A shift sleeve (34) is slidably
splined to the hub (32) and is moved by an operator shift force (Fo) and an
additive force (Fa) provided by the self-energizing ramp surfaces. Both forces (Fo
and Fa) react against the blocker teeth to engage the friction surfaces. The self-
energizing members (70, 72) are slidable relative to the hub and are axially
centered resiliency on the hub by detent assemblies (76, 78).